It has become acceptable to drive the cutterhead of a forage harvester in reverse while sharpening the knives of the cutterhead. U.S. Pat. No. 3,889,887 discloses one type of apparatus which has been used to reverse drive a cutterhead. With this type of apparatus, the main driveline is uncoupled from the cutterhead shaft and then coupled to an auxiliary or idler shaft in order to drive the cutterhead in reverse. In large forage harvesters, it is difficult to move the main driveline from one shaft to another shaft due to the size and weight of the main driveline.
The present invention overcomes this problem by providing drive means for a forage harvester wherein it is not necessary to move the main driveline from one shaft to another shaft to reverse drive the cutterhead. The drive means of the present invention comprises means mounted at the end of the cutterhead shaft. The which includes a hub connected to and movable along the cutterhead shaft between a driving position and a non-driving position with respect to the main driveline. The cutterhead may be driven forward when the hub is in the driving position and in reverse when the hub is in the non-driving position.
In the preferred embodiment of the present invention, the drive means also comprises a gearbox located between the hub clutch and the cutterhead with the cutterhead shaft passing through the gearbox. The gearbox contains two spur gears in meshing engagement, and one of the spur gears is fixed to the cutterhead shaft. The cutterhead may be driven in reverse through the two spur gears when the hub is in the non-driving position.